fix(cdn): align repository routing across pull zones (#165)

## Motivation

`cran.rpkgs.com` and `cran.allianceswisspass.devxy.io` serve the same B2 repository through separate Bunny pull zones, but only the first zone was managed and purged after weekly reindexing.
This allowed the Alliance endpoint to retain stale repository metadata and left locked `renv` restores unable to retrieve versions whose binary archive object was absent.

## Changes

- Adopt the Alliance SwissPass pull zone `3265648` into OpenTofu and configure it with the shared B2 origin and middleware script.
- Purge both Bunny pull zones after the weekly rebuild reindex.
- Preserve the requested public hostname in middleware redirects.
- Redirect missing archived binaries to the corresponding CRAN source package, checking whether the version is archived or still current.
- Cover the existing archived-binary passthrough behavior in the edge routing matrix.

## Verification

- `prek run -a`
- `just edge-test`
- `crow lint .crow/`
- `tofu validate`
- `bash -n scripts/purge_cdn_zone.sh`

## Deployment

Run `tofu apply` to adopt pull zone `3265648`, publish the middleware release, and align both pull zones.
After the apply, rerun the Alliance SwissPass CI restore that requested `cli 3.6.5` and `AzureStor 3.7.1`.

Reviewed-on: #165

scripts/purge_cdn_zone.sh

@@ -18,35 +18,38 @@
 # objects were replaced. The cost is a cold cache for everything else, which is
 # why this is not used by the daily update path.
 #
-# All hostnames on the zone (cran.devxy.io, cran.allianceswisspass.devxy.io,
-# cran.rpkgs.com) share pull zone 3857050, so one purge covers all of them.
+# The public hostnames currently use separate pull zones, so callers must pass
+# every zone that serves the repository.
 #
 # Usage:
-#   purge_cdn_zone.sh <BUNNYNET_API_KEY> <pull_zone_id>
+#   purge_cdn_zone.sh <BUNNYNET_API_KEY> <pull_zone_id> [<pull_zone_id>...]
 #
 set -euo pipefail
 
 if (($# < 2)); then
-  echo "usage: $0 <api_key> <pull_zone_id>" >&2
+  echo "usage: $0 <api_key> <pull_zone_id> [<pull_zone_id>...]" >&2
   exit 2
 fi
 
 api_key="$1"
-zone_id="$2"
+shift
 
-echo "Purging BunnyCDN pull zone ${zone_id}"
+for zone_id in "$@"; do
+  echo "Purging BunnyCDN pull zone ${zone_id}"
 
-status=$(
-  curl -sS -o /tmp/purge_zone_response.txt -w '%{http_code}' -X POST \
-    -H "AccessKey: ${api_key}" \
-    -H "Content-Length: 0" \
-    "https://api.bunny.net/pullzone/${zone_id}/purgeCache"
-)
+  response_file="/tmp/purge_zone_response_${zone_id}.txt"
+  status=$(
+    curl -sS -o "${response_file}" -w '%{http_code}' -X POST \
+      -H "AccessKey: ${api_key}" \
+      -H "Content-Length: 0" \
+      "https://api.bunny.net/pullzone/${zone_id}/purgeCache"
+  )
 
-if [[ "${status}" != "200" && "${status}" != "204" ]]; then
-  echo "Purge of pull zone ${zone_id} failed with HTTP ${status}:" >&2
-  cat /tmp/purge_zone_response.txt >&2
-  exit 1
-fi
+  if [[ "${status}" != "200" && "${status}" != "204" ]]; then
+    echo "Purge of pull zone ${zone_id} failed with HTTP ${status}:" >&2
+    cat "${response_file}" >&2
+    exit 1
+  fi
 
-echo "Purged pull zone ${zone_id} (HTTP ${status})"
+  echo "Purged pull zone ${zone_id} (HTTP ${status})"
+done